Nicaraguan lawmakers have approved a controversial plan to build a shipping waterway to rival the Panama Canal.

The National Assembly handed exclusive rights Thursday to an untested Chinese company to build a canal that would link Nicaragua's Caribbean coast with the Pacific Ocean, a project that could cost $40 billion, twice the size of the country's economy.

The HK Nicaragua Canal Development Investment company, led by Beijing entrepreneur Wang Jing, was handed a 50-year concession to first decide whether the project would be economically viable, and then possibly build and operate it. No specific route has been identified.

Shipping executives have voiced skepticism about whether there will be enough container shipping trade in the coming decades to support a second passage from the Atlantic to the Pacific. Environmental groups say they are worried about the canal's likely path through Lake Nicaragua, the country's main fresh water source.

But a lawmaker with the ruling Sandinista National Liberation Front, Carlos Emilio Lopez, said the canal could provide an economic boost for Nicaragua, one of the poorest nations in the Americas.

"This canal is an opportunity to lower the costs of import, the import of industrial products, of supplies and work tools. It's an opportunity to grow economically, to grow our national budget and to grow in accordance with the parameters used by the United Nations and (the UN Economic Commission for Latin America and the Caribbean)."